Optical semiconductor module

ABSTRACT

An optical semiconductor module with a downsizeable structure is provided. An optical semiconductor module  10  comprises a mounting member  20,  first member  30,  optical semiconductor element  22,  second member  34,  and optical fiber  40.  The mounting member  20  extends along a reference surface intersecting an axis  12.  The first member  30  has a tubular portion  30   a  extending in a direction of the axis  12,  a first end  30   b  formed at one end of the tubular portion  30   a  and fixed to the mounting member, and a second end  30   c  formed at the other end of the tubular portion  30   a.  The optical semiconductor element  22  is arranged in the tubular portion  30   a  of the first member  30  such that its optical axis is directed in a direction of the predetermined axis  12.  The second member  34  has a tubular portion  34   a  extending in a direction of the axis  12,  and is fixed to the second end  30   c  of the first member  20.  The optical fiber  40  extends in the tubular portion  34   a  of the second member  34  such that it is optically coupled to the optical semiconductor element  22.

TECHNICAL FIELD

[0001] The present invention relates to an optical semiconductor module.

BACKGROUND ART

[0002] A conventional optical semiconductor module 100 has a TO type CANcase 102, light-emitting element 104, optical fiber 106, ferrule 108,and support member 110. The light-emitting element 104 is accommodatedin the case 102. The optical fiber 106 is optically coupled to thelight-emitting element 104. The ferrule 108 supports the optical fiber106. The support member 110 supports the ferrule 108. The support member110 has a cylindrical shape extending in a direction along the opticalaxis of the light-emitting element 104, and is fixed to the side surfaceof the CAN case 102 through adhesive 112. This configuration enables theoptical fiber 106 to optically couple to the light-emitting element 104.

DISCLOSURE OF THE INVENTION

[0003] The inventor has made studies for developing a smaller version ofan optical semiconductor module. As the result of these studies, theinventor found a demand for decreasing the cross sectional area of theoptical semiconductor module in a surface perpendicular to the opticalaxis particularly in this technical field.

[0004] It is, therefore, an object of the present invention to providean optical semiconductor module having a structure allowing the abovedownsizing.

[0005] The inventor made further studies in order to realize thisobject.

[0006] First, the inventor made studies on the roles of componentscomposing the conventional optical semiconductor module. The TO type CANcase accommodates an optical semiconductor element, such as asemiconductor laser or a semiconductor light-receiving element. Asupport member serves to optically couple an optical fiber to thissemiconductor light-emitting element or semiconductor light-receivingelement. The support member has an insertion hole for defining adirection in which a ferrule holding the optical fiber is inserted. Thedirection of the ferrule is determined by the angle at which the CANcase is inserted in the insertion hole of the support member. In thesupport member, the inner diameter of the cylindrical portion isdetermined to be associated with the outer diameter of the CAN case.This structure enables the optical fiber to coincide with the opticalaxis of the light-emitting element when the support member is alignedwith the CAN case.

[0007] Subsequently, in the optical semiconductor module with componentsexhibiting these roles, the inventor made studies on the shape of theoptical semiconductor module in a cross section perpendicular to theoptical axis. The inventor found as follows: the support member has aportion accommodating the CAN case inserted thereto. It is difficult toreduce the cross section of this portion in the optical semiconductormodule as compared to the others of the optical semiconductor module.Therefore, what is needed is to reduce the cross sectional area of thisportion in the optical semiconductor module.

[0008] The inventor continued the studies on a structure that implementsthe reduction, and eventually invented the following.

[0009] An optical semiconductor module according to the presentinvention comprises a mounting member, a first member, an opticalsemiconductor element, a second member, and an optical waveguide. Themounting member extends along a reference plain intersecting apredetermined axis. The first member has a tubular portion, first andsecond ends, said tubular portion extending in a direction of thepredetermined axis, a first end being provided at one end of the tubularportion, and a second end being provided at the other end of the tubularportion. The first end is secured to the mounting member. The opticalsemiconductor element is arranged in the tubular portion of the firstmember such that its optical axis extends in a direction of thepredetermined axis. The second member has a tubular portion extending ina direction of the predetermined axis, and is secured to the second endof the first member. The optical waveguide is provided to pass throughin the tubular portion of the second member such that it is opticallycoupled to the optical semiconductor element.

[0010] Since the first member is secured to the mounting member, themounting member and first member define a space for accommodating theoptical semiconductor element. The second member defines a direction inwhich the optical waveguide extends. The second member is secured to thesecond end of the first member. This securing determines the directionin which the optical semiconductor element can be optically coupled tothe optical waveguide.

[0011] Since the mounting member and first member define theaccommodating space for the optical semiconductor element, thisconfiguration does not need any support member surrounding a CAN casetherewith as in the conventional optical semiconductor module.Therefore, the optical semiconductor module is provided with a structureenabling the downsizing thereof.

[0012] In the present invention, one or more features that will bedescribed below can be combined with each other arbitrarily.

[0013] The optical semiconductor module according to the presentinvention can further comprise a ferrule. The ferrule can be arranged inthe tubular portion of the second member, and can be secured thereto.The optical waveguide may include an optical fiber supported by theferrule.

[0014] The ferrule is guided by the tubular portion, and is arranged inthe tubular portion of the second member while supporting the opticalfiber. This configuration enables the optical fiber to be opticallycoupled to the optical semiconductor element. Since the ferrule issecured to the second member, the optical coupling becomes stabilized.

[0015] The optical semiconductor module according to the presentinvention further comprises a third member having a tubular portion anda pair of openings. The tubular portion of the third member extends in adirection of the predetermined axis, and accommodates the second memberand the ferrule. The openings are arranged at two ends of the tubularportion. The optical fiber passes through one opening of the pair ofopenings to the ferrule.

[0016] The second member and ferrule are arranged in the tubular portionof the third member, and are protected by the tubular portion. Since theoptical fiber passes through one opening of the pair of openings, thethird member guides the optical fiber so as to extend toward theferrule, thereby defining a range in which the optical fiber can bebent. This structure suppresses an unexpected force from being appliedto the optical fiber at a position where the optical fiber is insertedin the ferrule.

[0017] In the optical semiconductor module according to the presentinvention, the ferrule has first and second end faces. The optical fibercan be arranged to extend from the first end face toward the second endface of the ferrule. The ends of the optical fiber appear at both thefirst and second end faces, respectively. Hence, one of the first andsecond end faces can be optically coupled to the optical semiconductorelement. The other one of the first and second end faces can beoptically coupled to another optical fiber.

[0018] The optical semiconductor module according to the presentinvention further comprises a sleeve in which the ferrule is inserted.The second member has a depressed portion provided in an inner wallsurface of the tubular portion. The sleeve can be arranged in thedepressed portion of the second member.

[0019] The sleeve is accommodated in the depressed portion provided in apredetermined position of the second member, thereby determining theposition of the ferrule.

[0020] In the optical semiconductor module according to the presentinvention, the tubular portion of the second member has first and secondportions adjacent to each other in a direction of the predeterminedaxis. The first portion accommodates the ferrule. The second portion isprovided so as to arrange another ferrule. Another ferrule holds anotheroptical fiber that should be optically coupled to the optical fiber.When the other ferrule is inserted in the second member, the otheroptical fiber is optically coupled to the optical semiconductor element.The inner wall surface of the tubular portion guides the other opticalfiber which is being inserted, and the sleeve enables the opticalalignment of the other optical fiber.

[0021] The optical semiconductor module according to the presentinvention further comprises a lens provided between the opticalwaveguide and the optical semiconductor element. This lens enables theoptical tight coupling between the optical semiconductor element and theoptical waveguide.

[0022] In the optical semiconductor module according to the presentinvention, the optical semiconductor element can be either one of alight-emitting element and a light-receiving element. If the opticalsemiconductor element is a light-emitting element, it can provide anoptical signal to the optical fiber. If the optical semiconductorelement is a light-receiving element, it can receive the optical signalfrom the optical fiber and convert it into an electrical signal.

[0023] In the optical semiconductor module according to the presentinvention, the first member is secured to the mounting member at anannular connecting portion. The annular connecting portion is so formedas to surround a straight line on the optical axis of the opticalsemiconductor element. Since the annular connecting portion is providedto be highly symmetric with respect to the optical axis, it averagesdisplacement of the first member in securing it.

[0024] In the optical semiconductor module according to the presentinvention, the mounting member can be included in a cylindrical shape,having the center axis perpendicular to the reference surface and across section having a diameter of 4 mm or less. With the structures ofthe optical semiconductor module that has been already described in thisspecification and will be described hereinafter, optical semiconductormodules that can be accommodated in a cylindrical shape with a diameterof 4 mm or less can be realized.

BRIEF DESCRIPTION OF DRAWINGS

[0025] The above and other objects, features and advantages of thepresent invention will be readily apparent from the following detaileddescription of the preferred embodiments of the present invention whichwill be made with reference to the following accompanying drawings.

[0026]FIG. 1 is a perspective view of an optical semiconductor moduleaccording to the first embodiment of the present invention;

[0027]FIG. 2 is a sectional view of the optical semiconductor moduleaccording to the first embodiment of the present invention;

[0028]FIG. 3 is a perspective view of an optical semiconductor moduleaccording to the second embodiment of the present invention;

[0029]FIG. 4 is a sectional view of an optical semiconductor moduleaccording to the second embodiment of the present invention;

[0030]FIGS. 5A and 5B are views showing the relationship between asecuring member and the optical semiconductor module; and

[0031]FIG. 6 is a view showing a conventional optical semiconductormodule.

BEST MODES FOR CARRYING OUT THE INVENTION

[0032] The teachings of the present invention can be easily understoodin consideration of the following detailed description with reference tothe accompanying drawings. In the drawings, the same elements aredenoted by the same reference numerals, if possible

[0033] (First Embodiment)

[0034] An optical semiconductor module 10 according to an embodiment ofthe present invention will be described with reference to FIGS. 1 and 2.The optical semiconductor module 10 has a mounting member 20, an opticalsemiconductor element 22, a first member 30, second member 34, and anoptical waveguide 40. The optical semiconductor module 10 also hascondenser means, such as a lens 32, provided between the opticalsemiconductor element 22 and optical waveguide 40. The opticalsemiconductor module 10 has a sleeve 36 and a ferrule 38, and theferrule 38 is inserted in the sleeve 36. The sleeve 36 and ferrule 38can be accommodated in the second member 34, and the optical waveguide40 contains an optical fiber held by the ferrule 38.

[0035] In the optical semiconductor module 10, the following componentsare arranged in a direction of an axis 12: the mounting member 20, theoptical semiconductor element 22, the first member 30, the lens 32, thesecond member 34, the sleeve 36, the ferrule 38, and the opticalwaveguide 40. The predetermined axis can be selected to coincide with anoptical axis associated with the optical semiconductor element 22. Thefollowing description will be made for an optical semiconductor modulehaving an optical fiber adopted as the optical waveguide. In theembodiment, the optical fiber is an optical waveguide with a core and acladding provided around the core. A coated optical fiber is an opticalwaveguide covered with a resin, and the coated optical fiber has adiameter of about 250 μm. The coating resin is stripped-off in a part ofthe coated optical fiber such that the stripped-off part can be insertedin the ferrule.

[0036] The mounting member 20 can be a plate-like member, e.g., ametallic member processed by plating an iron member with gold, extendingalong a reference plane intersecting the predetermined axis 12. Themounting member 20 has a element mounting surface 20 a and a terminalarranging surface 20 b both extending along the reference plain. Theelement mounting surface 20 a has a support projection 20 c extending ina direction of the predetermined axis 12. The support projection 20 chas a support surface 20 d for mounting the optical semiconductorelement 22 thereon, and the support surface 20 d extends in a directionof the predetermined axis 12. The optical semiconductor element 22, suchas a light-receiving element and light-emitting element, is arranged onthe support surface 20 d .

[0037]FIG. 1 exemplifies the optical semiconductor module 10 employingthe optical semiconductor element 22, such as a semiconductor laserelement, but an optical semiconductor element 22, such as alight-emitting diode, can be also employed. A Fabry-Perot type laserdiode or DFB type laser diode each having a multiple quantum wellstructure constituted by InGaAsP/InP can be employed as a semiconductorlaser element of the 1.3 μm band. As a semiconductor laser element witha wavelength in the 1.55 μm band, a Fabry-Perot type laser diode or DFBtype laser diode each having a multiple quantum well structureconstituted by InGaAsP/InP can be employed. Alternatively, alight-receiving element such as a surface light-receiving photodiode canbe also used in place of the light-emitting element if it is arrangedsuch that its optical axis can be aligned with the optical fiber. Inthis case, the light-receiving surface of the light-receiving elementintersects the predetermined axis 12 at a predetermined angle, e.g., aright angle.

[0038] In accordance with an example shown in FIG. 1, an opticalsemiconductor module including a semiconductor laser as the opticalsemiconductor element 22 will be described. The optical semiconductorelement 22 has a light-emitting surface and light-reflecting surface soas to form an optical cavity, and is arranged on a mounting componentmade of insulating material 26 a , e.g., a heat sink or submount, suchthat its light-emitting surface and light-reflecting surface intersectthe predetermined axis 12. A monitoring light-receiving element 24 isarranged on a mounting component made of insulating material 26 b ,e.g., a submount, such that c is faced with the light-reflectingsurface, i.e., the light-receiving surface intersects the predeterminedaxis. Hence, an electrical signal available for monitoring the operationstate of the optical semiconductor element 22 is supplied from themonitoring light-receiving element 24, such as a surface light-emittingphotodiode. The mounting component 26 b is secured on the mountingcomponent 26 a .

[0039] The terminal arranging surface 20 b has one or more terminalelectrodes 28, e.g., four terminal electrodes 28 in this embodiment. Theterminal electrodes 28 extend in a direction of the predetermined axis12, and are inserted in holes extending from the element mountingsurface 20 a to the terminal arranging surface 20 b . The terminalelectrodes 28 have outer terminal portions projecting from the terminalarranging surface 20 b , and inner terminal portions projecting from theelement mounting surface 20 a . The light-emitting element 22 andlight-receiving element 24 are electrically connected to the innerterminal portions through the connecting members 28, such as bondingwires. The terminal electrodes 28 are secured to the mounting member 20through insulating members 28 a . The insulating members 28 aelectrically isolate the terminal electrodes 28 from the mounting member20. The terminal electrode 28 is also secured to the mounting member 20without the insulating members 28 a , whereby this terminal electrode 28is electrically connected to mounting member 20. Therefore, the mountingmember 20 and second member 30 are grounded in this embodiment while theoptical semiconductor module 10 operates.

[0040] The first member 30 has a tubular portion 30 a , first endportion 30 b , and second end portion 30 c . The tubular portion 30 aextends along the predetermined axis 12. The first end portion 30 b isformed at one end of the tubular portion 30 a . The second end portion30 c is formed at the other end of the tubular portion 30 a . The firstmember 30 can be made of a metal, such as stainless steel. The first endportion 30 b has a fixing surface 30 d that comes into contact with themounting member. The fixing surface 30 d has a projection 30 e providedso as to surround the axis 12. The first member 30 is joined with themounting member 20 such that the fixing surface 30 d faces a contactsurface 20 e of the mounting member 20. For example, this fixing can beperformed in the following manner. The first member 30 is arranged onthe mounting member 20 such that the annular projection 30 e comes intocontact with the contact surface 20 e . A current exceeding apredetermined value is applied through the mounting member 20 and firstmember 30. Since this current is concentrated at the annular projection30 e , Joule heat is generated mainly at this projection to heat it.When this temperature at the projection exceeds the melting point, theannular projection 30 e is melted. Because of this melting, the mountingmember 20 is welded to the first member 30. The continuous weldedportion is formed by this securing, so that the hermetical sealing isobtained at this bonding portion and the mounting member 20 iselectrically connected to the first member 30. The mounting member 20and first member 30 can be grounded through a terminal electrode 28.This terminal electrode 28 is electrically connected to the mountingmember 20 without the insulating members 28 a .

[0041] The tubular portion 30 a has an inner wall surface 30 f extendingin the direction of the predetermined axis 12. The inner wall surface 30f has an annular projection 30 h provided so as to support the lens 32.The projection 30 h extend so as to forms a lens arranging hole 30 idefined by a retaining surface 30 g surrounding the axis 12. The lens 32is accommodated in the lens arranging hole 30 i , and is bonded to thefirst member 30 through an adhering member 42, such as anultraviolet-curing resin or thermosetting resin. The adhering member 42is annularly formed such that the lens 32 can adhere to retainingsurface 30 g . The shape of the adhering member 42 is ensures thehermetical sealing at the adhering portion. The second end portion 30 chas an end face 30 j for supporting the second member 34. The lensarranging hole 30 i can position the lens 32. The lens 30 bonded facesthe light-emitting surface of the optical semiconductor element 22.

[0042] When the first member 30 is placed on the mounting member 20, theparts mounting surface 20 a , inner wall surface 30 f , and projection30 g define a space where the optical semiconductor element 22 is to beaccommodated. Hence, the first member 30 serves as a housing oraccommodating member. The annular projection 30 e and adhering member 42allows the hermetical sealing of the accommodating space, and theoptical module has a structure that does not contain a TO type CAN case,so that the optical module becomes smaller in size.

[0043] The second member 34 has a tubular portion 34 a extending in thedirection of the predetermined axis 12. The second member 34 can be madeof a metal, such as stainless steel. The tubular portion 34 a has anopening for inserting the sleeve 36 and ferrule 38 at one end 34 bthereof. Thus, the end portion 34 b has a taper surface 34 d . Thetubular portion 34 a also has an opening on the other end 34 c throughwhich light from the optical semiconductor element 22 passes.

[0044] The second member 34 has a fixing surface 34 e provided so as toface the second end face 30 j of the first member 30. The second member34 is aligned with the first member 30 to ensure the introduction of thelight. The second member 34 is joined to the first member 30 at theouter surface of the fixing surface 34 e . This securing of the secondmember 34 is achieved by a plurality of portions 48 a and 48 b (see FIG.2). This securing is carried out at these positions by a YAG laser beam,for example. The securing portions formed by laser welding are arrangedhighly symmetrically. These symmetrical securing portions reducedistortion that may be caused by securing. This structure allows theoptical coupling of the optical fiber 40 to optical semiconductorelement 22 without degradation of the optical coupling.

[0045] The second member 34 has an inner wall surface 34 f extending inthe direction of along the axis 12. The inner wall surface 34 f definesa region for accommodating the sleeve 36 and ferrule 38, and a directionin which the sleeve 36 and ferrule 38 are guided. The inner wall surface34 f has a depressed portion 34 g for accommodating the sleeve 36. Thedepressed portion 34 g is provided so as to form a closed loop about theaxis 12. The depressed portion 34 g can be a depression having a widthand a depth determined such that the sleeve 36 is accommodated.

[0046] As the second member 34 is a cylindrical member, a sleeve 36,such as a split sleeve is preferably arranged in the depressed portion34 g . The sleeve 36 shown in FIG. 1 is a split sleeve, and has atubular portion 36 a and gap 36 b . The tubular portion 36 a has a shapeof a circular columnar shell extending in a direction of a predeterminedaxis. The gap 36 b forms a pair of edges extending in a direction of thepredetermined axis in the tubular portion 36 a . Hence, the split sleeveis inserted in the depressed portion 34 g of the second member 34 suchthat the distance of the gap 36 b , i.e., the interval of the edges, isdecreased. After the split sleeve has inserted therein, the reduced gap36 b is relieved, so the outer surface of the sleeve 36 comes intocontact with the wall surface of the recess 34 g , thereby fixing theposition of the sleeve 36.

[0047] The second member 34 has an outer wall depressed portion 34 i inits outer wall surface 34 h . This depressed portion 34 i forms a flangeon the second terminal 34 c . The outer wall depressed portion 34 i hasa surface 34 m extending along the fixing surface 34 e . When the outerwall depressed portion 34 i is irradiated with the YAG laser at aplurality of positions, the second member 34 and first member 30 can bewelded to each other at the welded portions 48 a and 48 b (see FIG. 2).The outer wall depressed portion 34 i is used to facilitate the securingof the second member 34 and first member 30 to the fixing surface 34 eafter the second member 34 and first member 30 are aligned. When thisembodiment is employed, the plurality of fixing portions 48 a and 48 bcan be formed simultaneously.

[0048] The ferrule 38 is accommodated in the sleeve 36, and the ferrule38 is positioned in the first member 30 by the fastening force of thesleeve 36. Alternatively, the ferrule 38 may be secured to the sleeve 36by welding, for example. The position of the ferrule 38 is secured tothe first member 30, whereby this securing ensues optical couplingbetween one end 40 a of the optical fiber 40 and the lens 32. Theposition of the ferrule 38 can be changed in accordance with the focallength of the lens 32.

[0049] The ferrule 38 has a first end face 38 a , second end face 38 b ,and a hole 38 c extending from the first end face 38 a to the second endface 38 b in a direction of the axis 12. The resin coated on the opticalfiber 40 is partly removed and then the resin-removed portion of theoptical fiber 40 is inserted in the hole 38 c . Preferably, the firstand second end faces 38 a and 38 b are polished after the optical fiber40 is inserted in the hole 38 c . This polishing ensures that the endsof the optical fiber 40 appear at the respective end faces 38 a and 38b.

[0050] The first end face 38 b may be polished to form a first angle,e.g., substantially a right angle, with respect to the axis 12 of theoptical semiconductor module 10. This end face 38 b facilitates opticalcoupling between the optical fiber 40 and an optical fiber (in FIG. 1,an optical fiber 46 inserted in another ferrule 44) that is opticallycoupled to the semiconductor optical module 10. In more detail, forexample, the ferrule 44 is polished to form a taper at one end 44 a . Bythis polishing, the optical fiber 46 has an lensed end at the end 46 a .A lensed end 46 a can come into physical contact with the end face 38 aof the ferrule 38.

[0051] The second end face 38 c may be inclined at a second angle α,e.g., about an angle of 6 degrees, larger than an angle of 0 degree withrespect to the axis 12 of the optical semiconductor module 10. Theinclined end face 38 c is useful to decrease the amount of lightreflected from the second end face 38 c of the ferrule 38 and returningto the optical semiconductor element 22.

[0052] Referring to FIG. 2, the tubular portion 34 a of the secondmember 34 has first and second portions 34 j and 34 k , which areadjacent to each other in a direction of the axis 12. The first portion34 j accommodates the ferrule 38. The second portion 34 k is formed suchthat another ferrule (44 in FIG. 1) can be inserted in it. The otherferrule holds another optical fiber (40 in FIG. 1) that should beoptically coupled to the optical fiber 40.

[0053] As described above in detail, the mounting member 20 is formedsuch that it is included in a cylindrical shape having a diameter Lsatisfying L ≦4 mm and the center axis 12 perpendicular to the referenceplane. Also, the mounting member 20, the first member and the secondmember 34 can be formed such that they are included in a cylindricalshape having a diameter L satisfying L ≦4 mm and the center axis 12perpendicular to the reference plane. In other words, an opticalsemiconductor module has been provided with a structure that can makethe optical semiconductor module smaller.

[0054] (Second Embodiment)

[0055] An optical semiconductor module 14 according to anotherembodiment will be described with reference to FIGS. 3 and 4. Theoptical semiconductor module 14 has a mounting member 20, opticalsemiconductor element 22, first member 60, second member 64, and opticalwaveguide 70. The optical semiconductor module 14 can also have acondensing means, such as a lens 62, provided between the opticalsemiconductor element 22 and an optical waveguide 70. A ferrule 68 canbe accommodated in the second member 64. The optical waveguide 70 mayinclude an optical fiber supported by the ferrule 68. One end of theoptical waveguide 70 is optically coupled to the optical semiconductorelement 22, and the other end thereof reaches an optical connector plug74. Furthermore, in the optical semiconductor module 14, the opticalfiber 70 is inserted in the ferrule 68.

[0056] In the optical semiconductor module 14, the mounting member 20,the optical semiconductor element 22, the first member 60, the lens 62,the second member 64, a guide member 66, the ferrule 68, the opticalwaveguide 70, and the optical connector plug 74 are arranged in adirection of an axis 16. FIGS. 3 and 4 show the mounting member 20identical with that shown in FIGS. 1 and 2, but the present invention isnot limited thereto.

[0057] The first member 60 has a tubular portion 60 a extending in adirection of the predetermined axis 16, a first end 60 b provided at oneend of the tubular portion 60 a , and a second end 60 c provided at theother end thereof. The first member 60 may be a member made of metal,such as stainless steel. The first end 60 b has a securing surface 60 dthat comes into contact with the mounting member 20. The securingsurface 60 d has an annular projection 60 e continuous to surround theaxis 16 thereon. The first member 60 is secured to the mounting member20 such that the securing surface 60 d faces a contact surface 20 e .This securing is carried out in a method similar to that of the firstembodiment while obtaining the same advantages and functions as those ofthe first embodiment, but it is not limited thereto.

[0058] The tubular portion 60 a has an inner wall surface 60 f extendingin a direction of the predetermined axis 16. The inner wall surface 60 fhas an annular projection 60 h provided to support the lens 62. Theprojection 60 h has a support surface 60 g provided to support the lens62. After the lens 62 is arranged in the tubular portion 60 a andpositioned by the projection 60 h , the lens 62 is secured to the firstmember 60 through an adhering member 78 (FIG. 4). Hence, thelight-emitting surface of the optical semiconductor element 22 faces thelens 62.

[0059] If the adhering member 78 (FIG. 4) is provided annularly toadhere the lens 62 to inner wall surface 60 f , and it ensure thehermetical sealing at the adhering portion. The position of theprojection 60 h should be determined in consideration of the focallength of the lens 62 as well as the distance between the lens and theoptical semiconductor element 20. The second end 60 c has its end face60 j for supporting the second member 64.

[0060] When the first member 60 is secured on the mounting member 20, apart mounting surface 20 a , the inner wall surface 60 f , and theprojection 60 g define a region for accommodating the opticalsemiconductor element 22. Hence, the first member 60 serves as a housingor accommodating member. The annular projection 60 e and adhering member78 ensure the hermetical sealing of the accommodating space. The opticalsemiconductor module 14 is provided with a structure capable of reducingit in size because it does not contain any TO type CAN case.

[0061] The second member 64 has a tubular portion 64 a extending in adirection of the predetermined axis 16. The second member 64 may be asleeve made of stainless steel. At one end 64 b of the tubular portion64 a , an opening for inserting the ferrule 38 therein is formed. At theother end 64 c , an opening is provided such that light from the opticalsemiconductor element 22 passes therethrough. A flange is formed on theother end 64 c .

[0062] The second member 64 has a securing surface 64 e arranged so asto face the second end face 60 j of the first member 60. The secondmember 64 is aligned with the first member 60 so that it can be alignedwith the ferrule 68 that is to be inserted in the second member 64. Thesecond member 64 is secured to the first member 60 at the securingsurface 64 e , but this securing is not limited thereto. The securingcan be performed in the same manner as in the first embodiment, therebyobtaining the same functions and advantages as those of the firstembodiment.

[0063] The second member 64 has an inner wall surface 64 f extending isa direction of the axis 16. Hence, the inner wall surface 64 f defines aregion for accommodating the ferrule 68. The inner wall surface 64 fcomes into contact with the-outer surface of the ferrule 68, therebydefining the inserting direction for the ferrule 68. The ferrule 68 issecured to the second member 64. Thus, this securing enables opticalcoupling between the optical waveguide 70, inserted in the ferrule 68,and the optical semiconductor element 22.

[0064] The ferrule 68 has a first end face 68 a , second end face 68 b ,and hole 68 c extending from the first end face 68 a to the second endface 68 b in a direction of the axis 16. The coating resin isstripped-off in a part of the coated optical fiber such that thestripped-off part can be inserted in the ferrule. The optical fiber 70is inserted in the hole 68 c . Preferably, the second end face 68 b ispolished after the optical fiber 70 is inserted in the hole 68 c . Thispolishing facilitates an end 70 a of the optical fiber 70 appear at thesecond end face 68 b .

[0065] The second end face 68 c may be inclined at a first angle βexceeding an angle 0 degree with respect to the axis 16 of thesemiconductor module 14. A value almost equal to that in the firstembodiment can be employed as the value of the first angle, whereby thesame functions and advantages as those in the first embodiment areobtained, but the angle is not limited thereto.

[0066] The optical fiber 70 extends through the through hole 68 c of theferrule 68, and an accommodating portion 72 a of a third member such asa protecting member 72. The protecting member 72 has the accommodatingportion 72 a extending in a direction of the predetermined axis 16. Theaccommodating portion 72 a defines a tubular region having first andsecond openings. The second member 64 and the ferrule 68 with theoptical waveguide 70 inserted therein both can be inserted in theaccommodating portion 72 a from a first opening 72 e , and the opticalfiber 70 can extend through a second opening 72 f .

[0067] Referring to FIG. 4, the accommodating portion 72 a of theprotecting member 72 has a first portion 72 b , second portion 72 c andthird portion 72 d , which are arranged in a line and are adjacent toeach other. The second member 64 and ferrule 68 are accommodated in thefirst portion 72 b . The optical fiber 70 extends through the secondportion 72 c . The third portion 72 d supports the optical fiber 70. Theoptical fiber 70 flexes in the second portion 72 c so as to adjust itsdisplacement between the protecting member 72 and ferrule 68.

[0068] The protecting member 72 is made of elastic material such asflame-retardant rubber. Hence, the protecting member 72 can accommodatethe ferrule 68 and can moderate the bending force acting on the opticalfiber 70. This protects the optical fiber 70.

[0069] Referring to FIG. 3, the optical connector 74 is provided at theother end of the optical waveguide 70. The optical connector 74 has ahousing 80 and a ferrule 76 secured to the housing. The housing 80 holdsthe ferrule 76 such that it extends in a direction of the predeterminedaxis 16. The other end 70 b of the optical waveguide 70 appears at oneend of the ferrule 76.

[0070]FIG. 4 shows a propagation path for light generated by the opticalsemiconductor element 22.

[0071] As described above in detail, according to this embodiment, themounting member 20, first member 60, and second member 64 are formedsuch that they are included in a cylindrical shape having a diameter Lsatisfying L ≦4 mm and the center axis 12. Therefore, opticalsemiconductor modules have been provided with structures capable ofdownsizing them.

[0072]FIGS. 5A and 5B show securing members 90 and 94 for securing theoptical semiconductor module 10 shown in the first embodiment to awiring board. Explanation will be made in terms of the opticalsemiconductor module 10 shown in the first embodiment, but thesemiconductor module 14 according to the second embodiment is used inplace of that of the first embodiment as well.

[0073] Referring to FIG. 5A, the securing member 90 comprises a modulesupport portion 90 a having a half-annular shape and a pair of placementportions 90 b . The module support portion 90 a has a contact surface 90d surrounding the mounting member 20 of the optical semiconductor module10, and supports the optical semiconductor module 10. The module supportportion 90 a has a notch 90 e . The notch 90 e enables the opticalsemiconductor module 10 to be easily inserted in the securing member 90.The placement portions 90 b have contact surfaces 90 c extending in adirection of the axis 12, and come into contact with a wiring board 98 a. The placement portions 90 b have a pair of holes 92 a and 92 b . Theoptical semiconductor module 10 is arranged such that the contactsurface 90 c of the fixing member 90 faces the wiring board 98 a . Inthis arrangement, fixing components such as bolts are respectivelyinserted in the pair of holes 92 a and 92 b , and then fasten them. Theoptical semiconductor module 10 is arranged such that the axis 12extends along the wiring board 98 a .

[0074] Referring to FIG. 5B, the securing member 94 has an annularmodule support portion 94 a and a pair of placement portions 94 b . Themodule support portion 94 a has a contact surface 94 d for surroundingthe mounting member 20 of the optical semiconductor module 10, and holdsthe optical semiconductor module 10. The placement portions 94 b areformed to come into contact with a wiring board 98 b , and have acontact surface 94 c intersecting the axis 12 at a right angle, forexample. The placement portions 94 b have a pair of holes 96 a and 96 b. The optical semiconductor module 10 is arranged such that the contactsurface 94 c of the securing member 94 faces the wiring board 98 b .With this arrangement, fixing components such as locking bolts and nutsare respectively inserted in the pair of holes 96 a and 96 b and fastenthem. The optical semiconductor module 10 has been secured such that theaxis 12 is directed in a direction intersecting the wiring board 98 b ,for example, in a direction perpendicular to the wiring board 98 b.

[0075] Although the principle of the present invention has beendescribed in the preferred embodiments thereof, it is recognized by aperson skilled in the art that the present invention can be changed inits arrangements and details without departing from the principle. Forexample, the vertical and horizontal sizes of the respective componentscan be changed as required. Therefore, we claim all changes andmodifications of the present invention without departing from the spiritand scope of the appended claims.

Industrial Applicability

[0076] As has been described above in detail, in the opticalsemiconductor module according to the present invention, since thetubular first member is placed on the mounting member, the mountingmember and first member define a region for accommodating the opticalsemiconductor element. The second member defines a direction in whichthe optical waveguide extends. Since the second member is arranged atthe second end of the first member, this arrangement determines thedirection in which the optical waveguide and optical semiconductorelement can be arranged to be optically coupled to each other. Since thefirst member defines the accommodating space for the opticalsemiconductor element, a support member does not need to be arrangedoutside a CAN case, unlike in the conventional optical semiconductormodule. Therefore, an optical semiconductor module with a downsizeablestructure was provided.

1. An optical semiconductor module comprising: a mounting memberextending along a reference plane intersecting a predetermined axis; afirst member having a tubular portion, a first end portion and a secondend portion, said tubular portion extending in a direction of thepredetermined axis, said first end portion being provided at one end ofthe tubular portion and being arranged on said mounting member, and saidsecond end portion being provided at the other end of the tubularportion; an optical semiconductor element arranged in the tubularportion of said first member such that an optical axis thereof isdirected in a direction of the predetermined axis; a second memberhaving a tubular portion extending in a direction of the predeterminedaxis, said second member being arranged on the second end of said firstmember; and an optical waveguide optically coupled to said opticalsemiconductor element, said optical waveguide extending in the tubularportion of said second member:
 2. An optical semiconductor moduleaccording to claim 1, further comprising a ferrule accommodated in thetubular portion of said second member, wherein said optical waveguideincludes an optical fiber supported by said ferrule.
 3. An opticalsemiconductor module according to claim 2, further comprising a thirdmember having a tubular portion and a pair of openings, said tubularportion extending in a direction of the predetermined axis andaccommodating said second member and said ferrule, and said pair ofopenings being provided at two ends of the tubular portion; wherein theoptical fiber extends through one of the pair of openings of said thirdmember to reach said ferrule.
 4. An optical semiconductor moduleaccording to claim 2, wherein said ferrule has first and second endfaces, and the optical fiber extends from the first end face to thesecond end face of said ferrule.
 5. An optical semiconductor moduleaccording to claim 4, further comprising a sleeve, said ferrule isinserted in said sleeve; wherein said second member has a depressedportion provided in an inner wall surface of the tubular portion, andwherein said sleeve being arranged in the depressed portion of saidsecond member.
 6. An optical semiconductor module according to claim 2or 4, wherein the tubular portion of said second member has first andsecond portions arranged in a direction of the predetermined axis,wherein the first portion accommodates said ferrule, and wherein thesecond portion is provided such that another ferrule can be insertedtherein.
 7. An optical semiconductor module according to claim 1,further comprising a lens provided between said optical waveguide andsaid optical semiconductor element.
 8. An optical semiconductor moduleaccording to claim 1, wherein said optical semiconductor element iseither one of a light-emitting element and a light-receiving element. 9.An optical semiconductor module according to claim 1, wherein said firstmember is secured to said mounting member at an annular connectingportion provided to surround the optical axis of said opticalsemiconductor element.
 10. An optical semiconductor module according toclaim 1, wherein said mounting member is included in a cylindrical shapehaving a diameter of not more than 4 mm and a center axis perpendicularto the reference surface.